Ease the use of a custom Browser with Api and OAuthConsumer

With this patch it is easier to pass a customized \Buzz\Browser to
\SensioLabs\Connect\Api\Api and \SensioLabs\Connect\OAuthConsumer
without the nedd to provide the endpoint to the constructor.
It also removes \SensioLabs\Connect\Buzz\Client\Curl which is
unsecure and not needed anymore.